High speed large capacity computers have come to be essential tools for fundamental biological research only within recent years, but the need for these research tools has grown explosively. There are three areas in particular which place especially heavy demands on computational resources: 1) DNA sequencing and the associated data base searches for homologies among genes and gene products; 2) Analysis and manipulation of the three- dimensional structure of large, complex molecules, especially receptors and their ligands; and 3) Quantification of complex movements in three dimensions. This proposal describes existing and projected needs for scientific computing capacity at The Salk Institute. It indicates how the capacity of the existing computer center is rapidly becoming exhausted and presents a plan for expanding that capacity by upgrading the present Digital Equipment Corporation PDP-11/785 that is dedicated to scientific purposes to a more powerful VAX 8550. The Salk Institute established a Biocomputing Center in January of 1981 to provide scientific computing capabilities for more than 190 M.D./Ph.D. investigators in the 19 laboratories at the institute. Initially, the facility had a single DEC PDP-11/780 which was subsequently duplicated and both machines were upgraded to PDP-11/785s in 1985. One of these machines is dedicated entirely to scientific purposes, but now requires the upgrading requested here. The increased computational power is required because: 1) the number of users now greatly exceeds the system's capacity; 2) the complexity of new applications requires a more powerful system; and 3) input/output bus bandwidth is inadequate for increased computational speed. Upgrading the present system will enhance not only existing research efforts at The Salk Institute in the board areas of molecular and cellular biology and neuroscience, but will also permit the development of new and more powerful research tools to support future efforts to integrate these areas in an interdisciplinary study of molecular communications among and within cells.